Inverses
Inverses
Logarithms
The graph in the previous example can be modeled by the function y = log2 x. Logarithms are the inverse of exponentials, just as subtraction is the inverse of addition, and division is the inverse of multiplication. Translating exponential functions into logarithmic functions always follows the form below:
y = bx is equivalent to logb( y) = x
The right-hand side above is pronounced, "log-base-b of y equals x". The value of the subscripted "b" is the base of the logarithm, just as b is the base in the exponential equation. And, just as the base b of an exponential is always positive and never equal to 1, so is the base b for a logarithm.
* Note: Finding the logarithm that corresponds to the exponential function will be covered in Algebra II. Look at the following examples as a way to introduce yourself to the idea that will be covered later.